1994 Chevy Cavalier Idle Issue

I seem to be having an idleing issue with my car. I recently replaced the head gasket on my vehicle. Before I did this it seemed to have an issue at idle. I put the vehicle in any gear but a forward gear and it would idle ok with just a small feeling of a miss. In drive or a forward gear it would idle so rough it would shake the dashboard. I changed the head gasket because it had a small seep at the drivers side front corner thinking that lower compression in that cylinder may cause this. When I completed this job, it still runs the same. Since I have put on a new tps, wires, plugs, iac, and map sensor. It still does the same thing. The ignition module tests good, and I have changed the coil packs as well. It seems to be "loading up" with fuel while running at an idle and all the plugs that I take out look the same. A lil sooty, and dark. We had it on a snap-on code scanner and we do not have any codes showing up. In your best opinion, do you think I may have a computer issue?